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Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for HD 189733: 07-07 (100), 07-08 (100), 07-09 (100), 07-10 (100), 07-11 (100) — by astronomy; check the weather when the night is within four days.
2026-06-30astronomy score per night — click a bar for that night2026-07-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-06-30 Tue 43 96 41 23:10–03:45 (marginal, 4.58 h) 71.1° 02:45 4.52 99% 48.8°
2026-07-01 Wed 43 27 11 23:10–00:00 (marginal, 0.83 h) 71.1° 02:45 4.54 96% 45.2°
2026-07-02 Thu 47 74 35 23:10–03:45 (marginal, 4.58 h) 71.1° 02:40 4.56 92% 43.9°
2026-07-03 Fri 78 31 24 02:00–03:00 (marginal, 1.0 h) 71.1° 02:35 4.58 86% 45.3°
2026-07-04 Sat 89 72 64 01:00–01:15 (good, 0.25 h) 71.1° 02:30 4.61 78% 49.3°
2026-07-05 Sun 96 89 86 23:10–03:00 (good, 3.83 h) 71.1° 02:25 4.64 70% 55.3°
2026-07-06 Mon 99 97 96 23:10–03:50 (good, 4.67 h) 71.1° 02:25 4.67 59% 62.9°
2026-07-07 Tue 100 96 96 23:10–03:50 (good, 4.67 h) 71.1° 02:20 4.7 49% 71.7°
2026-07-08 Wed 100 0 0 — 71.1° 02:15 4.73 38% 81.3°
2026-07-09 Thu 100 91 91 23:05–03:50 (good, 4.75 h) 71.1° 02:10 4.76 27% 91.5°
2026-07-10 Fri 100 97 97 23:05–03:55 (good, 4.83 h) 71.1° 02:05 4.8 17% 101.9°
2026-07-11 Sat 100 100 100 23:05–03:55 (good, 4.83 h) 71.1° 02:05 4.84 9% 112.0°
2026-07-12 Sun 100 89 89 23:05–03:55 (good, 4.83 h) 71.1° 02:00 4.87 3% 121.5°
2026-07-13 Mon 100 89 89 23:00–03:55 (good, 4.92 h) 71.1° 01:55 4.91 0% 129.3°
2026-07-14 Tue 100 98 98 23:00–04:00 (good, 5.0 h) 71.1° 01:50 4.96 0% 134.5°
2026-07-15 Wed 100 57 57 02:00–04:00 (good, 2.0 h) 71.1° 01:50 5.0 3% 136.1°
2026-07-16 Thu 100 22 22 23:00–00:00 (good, 1.0 h) 71.1° 01:45 5.04 9% 133.9°
2026-07-17 Fri 100 98 98 22:55–04:00 (good, 5.08 h) 71.1° 01:40 5.08 16% 128.8°
2026-07-18 Sat 100 94 94 22:55–04:05 (good, 5.17 h) 71.1° 01:35 5.13 25% 121.7°
2026-07-19 Sun 100 98 98 22:55–04:05 (good, 5.17 h) 71.1° 01:30 5.18 35% 113.6°
2026-07-20 Mon 100 54 54 02:00–04:05 (good, 2.08 h) 71.1° 01:30 5.22 45% 105.0°
2026-07-21 Tue 100 73 73 23:00–03:00 (good, 4.0 h) 71.1° 01:25 5.27 55% 96.3°
2026-07-22 Wed 100 96 96 22:50–04:10 (good, 5.33 h) 71.1° 01:20 5.32 64% 87.6°
2026-07-23 Thu 100 62 62 23:00–02:00 (good, 3.0 h) 71.1° 01:15 5.37 73% 79.0°
2026-07-24 Fri 100 0 0 — 71.1° 01:10 5.42 81% 70.8°
2026-07-25 Sat 100 87 87 01:00–04:15 (good, 3.25 h) 71.1° 01:10 5.47 88% 63.0°
2026-07-26 Sun 96 86 83 00:00–04:15 (good, 4.25 h) 71.1° 01:05 5.52 93% 56.0°
2026-07-27 Mon 59 99 58 02:30–03:00 (good, 0.5 h) 71.1° 01:00 5.58 97% 50.1°
2026-07-28 Tue 48 90 43 22:40–04:20 (marginal, 5.67 h) 71.1° 00:55 5.63 100% 45.9°
2026-07-29 Wed 45 100 45 22:40–04:20 (marginal, 5.67 h) 71.1° 00:55 5.68 100% 43.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-06-30&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.